Optical connector assembly, coupling device and method for aligning such a coupling device and a waveguide structure

ABSTRACT

The invention relates to an optical connector assembly for optically connecting to a waveguide structure in a x-y plane of a layer stack, wherein the connector assembly comprises a coupling device providing a first optical path, and the waveguide structure provides a second optical path, deflecting from said first optical path. The coupling device comprises first reference means adapted to co-operate with second reference means in the layer stack, wherein the second reference means are adapted for aligning the coupling device to the waveguide structure in both the x- and y-direction of the x-y plane as to optically couple the first and second optical path. As a result an optical connector assembly is provided that improves the optical coupling between the optical path in a waveguide structure and in a coupling device and/or a mating optical device. The coupling device may comprise third reference means to couple an optical connector to the waveguide structure. The invention also relates to a method for aligning the coupling device and the waveguide structure.

FIELD OF THE INVENTION

The invention relates to an optical connector assembly for opticallyconnecting to at least one waveguide structure in at least one x-y planeof a layer stack, said connector assembly comprising a coupling deviceproviding at least one first optical path, said waveguide structurecomprising at least one optical waveguide providing at least one secondoptical path deflecting from said first optical path, said couplingdevice comprising first reference means adapted to co-operate withsecond reference means in said layer stack. The invention furtherrelates to a coupling device for use in such an optical connectorassembly and to a method for aligning a coupling device to a waveguidestructure.

BACKGROUND OF THE INVENTION

An optical backplane, which may be a printed circuit board (PCB), isused to optically couple optical, optoelectrical devices or other PCB'sby providing an optical path over which optical signals can betransmitted. Usually optical waveguides are used for providing anoptical path to transmit these optical signals over the backplane. In ahybrid approach, these waveguides are integrated or embedded in thebackplane. Such a backplane is schematically shown in FIG. 1 and will bediscussed below. In order to reduce optical loss in the coupling of thiswaveguide structure and the components or other PCB's, alignment is akey issue in this area.

U.S. Pat. No. 6,236,788 B1 discloses an arrangement for aligning opticalcomponents, wherein an arrangement is provided for coupling light intoor out of a waveguide, that is positioned on a base plate. The baseplate supports a mirror mount. A holding device for holding optical oropto-electronic components, such as a lens or glass fibre connectors, isprovided as well. The mirror mount includes first alignment marks andthe holding device includes second alignment marks which snap togetherwith the first alignment marks to permit an alignment in a direction(x-direction) that is parallel to the waveguide. The holding deviceincludes third alignment marks and the base plate includes fourthalignment marks which are used for an alignment in a direction(y-direction) that is perpendicular to the waveguide

However, an alignment arrangement as disclosed in the prior art, doesnot provide an efficient optical coupling between the first optical pathin the holding device and the second optical path defined by thewaveguide structure, since the reference marks do not ensure properalignment. The reference marks only result in an independent alignmentin the x-direction or the y-direction. Simultaneous alignment in boththe x- and y-direction of the x-y plane is not ensured.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an optical connectorassembly that improves the optical coupling between a waveguidestructure and a coupling device.

This object is achieved by providing an optical connector assemblycharacterised in that said second reference means are adapted foraligning said coupling device to said waveguide or waveguide structurein both the x- and y-direction of said x-y-plane as to optically couplesaid first optical path and said second optical path. In this wayefficient optical coupling is achieved, since the x-direction and they-direction are aligned simultaneously.

Preferably the coupling device further comprises third reference meansfor aligning a mating optical device, providing a third optical path,with a waveguide or waveguide structure as to optically couple thesecond optical path and the third optical path. Since the firstreference means and third reference means may be manufactured in thesame process step or positioned relatively to each other in apredetermined manner, the coupling device can be manufactured to be anaccurate intermediate component for coupling the optical paths providedby the waveguide or waveguide structure and the mating device. Theoptical connector of such a mating optical device may have fourthreference means adapted to co-operate with the third reference means ofthe coupling device. The third and fourth reference means may be guidereference means, such as guide pins and corresponding holes or v-shapedridges and corresponding v-shaped grooves. The coupling device comprisesan area providing the first optical path. In an embodiment of theinvention this area may comprise an optical component such as a lens orlens array. Lenses can be advantageously applied to optimise coupling tomating devices and/or fibres thereof and to collimate diverging lightbeams.

In an embodiment of the invention the first optical path is deflectedunder a deflection angle with respect to the second optical path. Thisdeflection can be achieved by providing a reflective layer on a facet ofa waveguide of the waveguide structure. Such a deflection has theadvantage that the position of the deflective means in the z-directionis defined by the waveguide itself.

Moreover a mirror mount can be used to achieve the aforementioneddeflection. Such a mirror mount preferably has referencing means foralignment with the optical component, if present. Alignment of themirror mount with respect to the waveguide structure can be achieved byusing the second reference means in positioning this mirror mount by apick- and place machine. Moreover, the same or different referencingmeans on the mirror mount may be used to align this mirror mount and theoptical component.

The mirror mount may constitute an integral part of the coupling device,which coupling device may comprise the optical component as well. Thisis advantageous because in such an integrated coupling device, there areless degrees of freedom since movement between the mirror mount and theoptical component is disabled.

The deflection angle preferably is substantially ninety degrees. Such adeflection angle can be advantageously applied in a layer stack such asa printed circuit board (PCB) using the hybrid approach for the opticalbackplane.

In an embodiment of the invention the layer stack comprises multiplewaveguides in the x-y plane or over each other in the z-direction. Insuch an embodiment the reflective surfaces of the waveguides or themirror mount are adapted to deflect optical signals between the multiplesecond optical paths provided by these multiple waveguides andcorresponding first optical paths provided by the coupling device.

In a preferred embodiment of the invention the waveguide structure isadapted as to position the mirror mount in the second optical path.Preferably the mirror mount is positioned on the cladding layer. In thisway position control in the z-direction is obtained; insufficientposition control in the z-direction may negatively influence alignmentin the x-direction of the x-y plane. The same holds for the firstreference means if these means are guide reference means such as pins.Preferably these guide reference means define a plane parallel to thex-y plane. The mirror mount can be fixed to the waveguide structure byfilling a space, defined in at least in the cladding layer under themirror mount, with an adhesive substance. This adhesive substance exertsa pulling force to the mirror mount, holding this mirror mount inaccurate position. The mirror mount may be supported by supportstructure(s) provided in this space.

In an embodiment of the invention the first and second reference meanshave restricted dimensions in the x-y plane. Such second reference meansfacilitate simultaneous alignment in both the x- and y-direction.

In an embodiment of the invention the second reference means areprovided in the same layer of the layer stack. Preferably this layercorresponds to a layer of the waveguide structure or the top layer ofthe stack. In the first case, the second reference means can be appliedsimultaneously with one of the process steps for manufacturing thewaveguide structure, while in the second case the second reference meansare easily accessible for alignment.

In an embodiment of the invention the first and second reference meansare guide reference means or index reference means. Guide referencemeans are e.g. guide pins, extending in a direction perpendicular to thex-y plane (z-direction), and corresponding guide holes for fitting theguide pins for alignment. Index reference means are markings that arevisible to e.g. a pick and place machine for aligning the couplingdevice and the waveguide structure. It is to be noted that visibilitynot necessarily refers to visibility by the eye, but may also refer toe.g. visibility in the x-ray spectrum.

Finally the invention relates to a method for aligning a couplingdevice, providing a first optical path, and a waveguide structure,comprising at least one optical waveguide, in a x-y plane of a layerstack, said waveguide providing a second optical path, deflecting fromsaid first optical path, said coupling device comprising first referencemeans, said method comprising the steps of applying second referencemeans in at least one single layer of said layer stack in apre-determined x-direction and y-direction relative to said waveguidestructure and aligning said coupling device and said waveguide structureby matching said first reference means in the x- and y-direction of saidx-y plane with said second reference means.

U.S. Pat. No. 6,404,960 discloses a flexible optical connector assemblyfor connecting a flexible waveguide structure to an optical chip whereinalignment is achieved using reference means. This publication howeverdoes not relate to alignment of a device and a layer stack comprising anembedded waveguide structure, as is the case for a hybrid backplane.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention will be described into more detailbelow with reference to the attached drawing of which

FIG. 1 schematically illustrates the concept of an hybrid opticalbackplane;

FIGS. 2A-F schematically illustrate various approaches to deflect anoptical signal between optical paths;

FIGS. 3A, B show a first embodiment of the optical connector assemblyaccording to the invention;

FIGS. 4A-D show a second embodiment of the optical connector assemblyaccording to the invention;

FIGS. 5A-C show a third embodiment of the optical connector assemblyaccording to the invention;

FIG. 6 shows the coupling device coupled to the layer stack.

FIGS. 7A-F show an optical connector assembly including an opticalconnector of a mating device according to an embodiment of theinvention.

FIGS. 8A-D show a fourth embodiment of the optical connector assemblyaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a hybrid optical backplane or PCB 1, which is a layer stackcomprising several layers. Hereinafter this backplane 1 will also bereferred to as layer stack 1. The layer stack 1 comprises at least oneoptical waveguide 2 which may be part of a waveguide structure 3 (seeFIG. 3A) comprising multiple waveguides 2. The waveguide 2 is positionedin a x-y plane, which is the plane perpendicular to the figure in thiscase. Waveguide 2 or waveguide structure 3 is integrated or embedded inat least one of the layers of the layer stack 1. Embedded waveguides 2may be polymer waveguides, glass sheet waveguides or waveguides obtainedby embedded fibre technology.

Optical signals, transferred to or from a mating optical device, such asan optical device or optoelectrical device 4 or an other PCB 5, areprovided over a first optical path 6 to the waveguide 2 of the layerstack 1, which waveguide 2 provides a second optical path 7 to theoptical signal. In order to achieve an optimal optical coupling betweenthe first and second optical path, that are perpendicular to each otherfor the hybrid optical backplane here, a coupling device 8 is providedfor alignment purposes. Pre-alignment means are indicated with 9. Thecoupling device 8 and the way in which this coupling device 8 is alignedwith the waveguide 2 will be described in further detail hereinafter.

In order to enable the optical signal to be deflected between the firstoptical path 6 oriented in the z-direction and the second optical path 7oriented in the x-direction, various approaches can be taken. Examplesof these approaches are schematically illustrated in FIGS. 2A-F. It isnoted that although only perpendicular deflection is illustrated, otherdeflection angles are possible as well. The arrows indicate the opticalsignals.

The waveguide 2, being part of layer stack 1, comprises a top claddinglayer 10, a waveguide core 11 and a bottom cladding layer 12. Layerstack 1 may comprise various other layers below and/or above thewaveguide 2. Such a layer is e.g. copper layer 13, deposited below thewaveguide 2. Moreover the layer stack 1 may comprise several waveguides2 or waveguide structures 3 in the z-direction.

In FIGS. 2A-D deflection of optical signals between the first opticalpath 6 and the second perpendicular optical path 7 may be achieved byemploying a reflective layer 14 on a facet of the waveguide structure 3.

FIGS. 2A and 2C show that reflective layer 14 can be applied such thatoptical signals exhibit internal reflection, i.e. the optical signalsare substantially confined in the waveguide 2 upon reflection at thereflective layer 14. In FIG. 2C the internally reflective layer 14 iscombined with a coupling device 8 comprising an optical component 15such as a lens or lens array.

FIGS. 2B and 2D show the variant wherein the reflective layer 14 isapplied such that the optical signals exhibit external reflection, i.e.reflection takes place outside of the waveguide 2. The space 16 ispreferably filled with a material having the same refractive index asthe waveguide core. Again an optical component 15 can be applied as apart of the coupling device 8, as shown in FIG. 2D.

FIGS. 2E and 2F illustrate another approach for deflecting opticalsignals between a first optical path 6 and a second optical path 7 overninety degrees. Here, a mirror mount 17 is used that can be placedwithin the first and second optical path. Mirror mount 17 refers to anycomponent able to deflect an optical signal and thus may refer e.g. to agrating or a prism as well. Waveguide 2 is adapted to accommodate thismirror mount 17. The space 16 through which the optical signal travelspreferably is filled with an index matching material once more. Themirror mount 17 can be integrated with a coupling device a comprising anoptical component 15 such as a lens or lens array, as shown in FIG. 2E,as well as being as separate component, as shown in FIG. 2F. The mirrormount 17 may also be used without the optical component 15.

It is to be noted that in using the separate mirror mount 17, z-axiscontrol becomes an issue, since the waveguide 2 and the reflectiveinterface of the mirror mount 17 are not automatically lined up as forthe internal or external reflection approach. In FIG. 2E this problem isillustrated by the dashed line of the mirror mount 17 and the resultingoptical signal. It is observed that if the mirror mount 17 is notadequately positioned, i.e. the position of the mirror mount 17 in thez-direction is not in line with the second optical path 7, a shift ofthe optical signal in the x-direction may result. This problem isspecifically addressed in the second and third embodiment of theinvention, displayed in FIGS. 4 and 5.

The application of one or more optical components 15 may enhance oroptimise the optical coupling between the first optical path 6 and thesecond optical path 7. Lenses or lens arrays can e.g. be used tocollimate diverging light beams thereby avoiding optical loss.

In FIGS. 3A and 3B a first embodiment of the optical connector assemblyaccording to the invention is displayed. Layer stack 1 comprises awaveguide structure 3 having various waveguides 2. Waveguides 2 comprisea top cladding layer 10, a waveguide core 11 and a bottom cladding layer12. Cladding layers 10 and 12 are present outside the waveguidestructure 3 as well as to form a part of the layer stack 1. The facetsof the waveguide comprise a reflective layer 14 for employing theexternal deflection approach as explained above. By applying thereflective layer 14 on a facet of the waveguide itself, no measures haveto be taken to control the position of the reflective layer in thez-direction. The importance of z-direction control of a reflectivesurface was illustrated in FIG. 2E.

The optical connector assembly further comprises a coupling device 8providing a first optical path 6 via an area 18. The area 18 maycomprise a cavity and may be used to employ an optical component 15,such as a lens array for optimising the optical coupling of the opticalsignals of the waveguides 2. The lens or lens array may be provided inthe cavity as a separate component or may form an integral part of thecoupling device 8. The area 18 may as well be a region transparent tothe optical signals transmitted over the first optical path 6.

Coupling device 8 comprises first reference means 19 used for aligningcoupling device 8 in both the x-direction and the y-direction with thewaveguide structure 3 of the layer stack 1. This alignment is performedby applying second reference means 20 in a layer of the layer stack 1.In general, the second reference means 20 are applied in such a layer ina predetermined x-direction and y-direction relative to the waveguidestructure 3 such that when these second reference means 20 co-operatewith the first reference means 19, optimal optical coupling is achievedbetween the first optical path 6 and the second optical path 7.Preferably the second reference means 20 define a line parallel to they-direction and perpendicular to the second optical path 7. The firstreference means 19 on the coupling device 8 are manufactured to define aline parallel to the y-direction and the longitudinal axis of the area18 as well and at a predetermined position in the x-direction, such thatthe second reference means 20 may coincide with the first referencemeans 1920 during alignment.

Preferably the second reference means 20 are located in the same layerof the layer stack 1. In this embodiment this layer is the bottomcladding layer 12 of the waveguide structure 3. It is advantageous touse such a layer of the waveguide structure 3, since in that case thesecond reference means 20 can be applied simultaneously with orsubsequently to one of the process steps for manufacturing the waveguidestructure 3. These second reference means 20 can be accurately appliedin the preferred layer by using laser ablation or photolithography,being convenient techniques of manufacturing a waveguide structure 3. Itwill be appreciated that the second reference means 20 should remainavailable for alignment if further layers complete the layer stack 1.This may be done by covering the second reference means 20 and makingthem available after the layer stack 1 is completed. Alternatively thesecond reference means 20 can be applied on top of the layer stack 1.This provides the advantage of easy accessibility if the coupling device8 is to be positioned on the layer stack 1. In yet another alternative,the second reference marks 20 can be applied in the copper layer 13,underneath the bottom cladding layer 12 of the waveguide 2 or anotherlayer. The second reference means 20 can also be applied on top of thetop cladding layer 10 or on top of the mirror mount 17, as shown inFIGS. 7B and 7C.

The first reference means 19 and second reference means 20 preferablyare guide reference means or index reference means. The first referencemeans 19 may e.g. be guide pins, fitting in the second reference means20 being guide holes. In a variant, both the first reference means 19and the second reference means 20 may be guide holes whereas separateguide pins are provided if the coupling device 8 is coupled to the layerstack 1. Alternatively, the first reference means 19 and the secondreference means 20 are index reference means, being marks visible formachine placing of the coupling device 8 on the layer stack 1. Thesemarks can advantageously be applied during manufacturing of thewaveguide structure 3, since in that case accurate positioning of thesemarks with respect to the waveguide structure can be achieved. In FIG.3A the first reference means 19 and second reference means 20 are indexreference means.

Preferably the first reference means 19 and second reference means 20 donot exhibit a substantial dimension in the x-y plane (typically only afew microns), to facilitate simultaneous alignment in both thex-direction and the y-direction.

In FIG. 3B a cross-section across line A-A of FIG. 3A is shown, whereinthe coupling device 8 is positioned, using the first and secondreference means, in or on the layer stack 1 according to the invention.The three-dimensional representation of this case in shown in FIG. 6.

Coupling device 8 further comprises a reference plane 21 comprisingthird reference means 22. These third reference means 22 are furtherdiscussed below with respect to FIGS. 7A-D.

In FIG. 4A a second embodiment of an optical connector assemblyaccording to the invention is displayed. Most parts and features of theoptical connector assembly shown, have already been discussed above forthe first embodiment and are indicated with the same reference numerals.In FIG. 4A, the deflection approach discussed with respect to FIG. 2E isused. In this approach, a mirror mount 17 is integrated in the couplingdevice 8 to deflect optical signals between the first optical path 6 andthe second optical path 7, preferably together with an optical component15 such as a lens or lens array. As was already discussed above withrespect to FIG. 2E, this approach brings up the issue of the z-axiscontrol for the mirror mount 17, since the absence of a controlmechanism for the z-direction may result into misalignment in the x-yplane.

Apart from the features already discussed for FIG. 3A, the secondembodiment exhibits a space 23 in the layer stack 1 accommodatingsupport structures 24 that may be obtained from this layer stack 1.These features can also be observed from the cross-section A-A,displayed in FIG. 4B, where the coupling device 8 is positioned bymatching the first reference means 19 with the second reference means20.

Z-axis control is effectively achieved by defining support structures 24in the space 23 underneath the mirror mount 17. The mirror mount 17 ispositioned in accordance with the second optical path 7, by removinglayers from the layer stack 1, except from the support structures 24providing the height or z-axis control. These layers of the layer stack1 can be removed by e.g. laser ablation, grinding or etching in theregion where the mirror mount 17 is envisaged to be positioned. If e.g.only the bottom cladding layer 12 is removed, accurate z-axispositioning can be achieved. More layers of the layer stack 1, such ascopper layer 13, may be removed as well; this situation is illustratedin FIG. 4B. In order to keep the mirror mount 17 in accurate positionwith respect to the second optical path 7, an adhesive material 25 canbe applied in the space 23. Such an adhesive material may be an epoxyfill. If this epoxy hardens, a downward, pulling, force is exerted onthe mirror mount 17.

As shown in FIGS. 4C and D, the mirror mount 17 can be positioned in thesecond optical path 7 without the support structures 24. Alternatively,layers of the layer stack 1 support the mirror mount 17. In FIGS. 4C and4D the top cladding layer 10 of the waveguide structure 3 has been usedto position the mirror mount 17 in the second optical path 7.

In FIG. 5A a third embodiment of an optical connector assembly accordingto the invention is displayed. Most parts and features of the opticalconnector assembly shown, have already been discussed above for thefirst and second embodiment and are indicated with the same referencenumerals. In FIG. 5A, the deflection approach discussed with respect toFIG. 2F is used. In this approach, a separate mirror mount 17 is appliedto deflect optical signals, before the coupling device is attached tothe layer stack 1.

In FIG. 5B the situation is shown wherein the mirror mount 17 is broughtin position. This positioning can be achieved by providing the mirrormount 17 with reference means (not shown). These reference means mayfirst be used for picking up the mirror mount 17 by a pick and placemachine. Subsequently the separate mirror mount 17 is brought inposition by this machine, e.g. by using the second reference means 20 asa reference. The mirror mount 17 may comprise further reference as wellin order to accurately position a (provisional) optical component 15,having corresponding reference means, afterwards. As mentionedpreviously, the mirror mount 17 may comprises the second reference means20, as shown in FIGS. 7B and 7C. In this case these second referencemeans 20 can also be used to perform the above identified tasks.

As was already discussed above with respect to FIG. 2E and FIG. 4A,placing of a mirror mount that is not automatically in position withrespect to the second optical path 7 in the z-direction, brings up theissue of the z-axis control for the mirror mount 17, since the absenceof a control mechanism for the z-direction may result into less optimaloptical coupling between the first optical path 6 and the second opticalpath 7 in the x-direction. As shown in FIG. 5C, which displays across-section A-A identified in FIGS. 5A and 5B, the means applied herefor z-direction control may be similar to the ones applied in the secondembodiment.

After positioning, the coupling device 8 may be fixed to the layer stack1. This can be performed by applying adhesive material 25 under thecoupling device 8. Since this adhesive material may fill the space 16,located in both optical paths 6 and 7, preferably an index matchingmaterial, such as epoxy, may be used. In FIG. 6, the optical connectorassembly is shown for the first, second and third embodiment wherein thecoupling device 8 has been fixed to the layer stack 1.

In FIGS. 7A-D an embodiment of the optical connector assembly is shown,wherein the assembly further includes an optical connector 26 of amating device (not shown), providing a third optical path 27. In FIG. 7Aan overview of the optical connector assembly is displayed, while FIGS.7B-D show detailed parts of the assembly.

In FIG. 7A the layer stack 1 is shown with the coupling device 8 on top.Optical connector 26 providing the third optical path 27 to a matingdevice is intended for optically coupling to the waveguide structure 3in the layer stack 1.

FIGS. 7B and 7C show detailed views of the layer stack 1 in accordancewith FIG. 7A. FIGS. 7B and 7C correspond to the embodiments shown in theFIGS. 5A-C. For the sake of simplicity, mirror mount 17 is simply put ontop of the cladding layer, thereby disregarding the z-axis controlissue. Mirror mount 17 comprises the second reference means 20 foraligning the coupling device 8 to the waveguide structure 3 as to couplethe first optical path 6 of the coupling device 8 and the second opticalpath 7, provided by the waveguide structure 3. Coupling device 8comprises the first reference means 19 for this alignment and furtherincorporates a lens array 15, wherein a lens is provided for eachwaveguide 2 of the waveguide structure 3. First reference means 19 andsecond reference means 20 are index reference means. Coupling device 8further comprises third reference means 22 in order to align opticalconnector 26 with the coupling device 8.

Alignment of the optical connector 26 with the coupling device 8 isachieved by providing the optical connector 26 with fourth referencemeans 28, shown in FIG. 7D. The third reference means 22 and fourthreference means 28 are adapted such that good optical coupling isachieved between the second optical path 7 and the third optical path27. It is noted that upon connection of the mating device, the couplingdevice 8 may be a part of the layer stack 1, the pre-alignment means 9or the optical connector 26.

In FIGS. 7E and 7F an embodiment of the invention is depicted, whereinthe layer stack 1 comprises, two waveguide structures 3 in a single x-yplane of the layer stack 1. A single mirror mount 17 is placed betweenthe waveguide structures 3 with the reflecting surfaces facing thewaveguide structures 3. The mirror mount 17 comprises second referencemeans 20 for alignment of the coupling device 8 with the waveguidestructures 3. The waveguide structures 3 each provide a second opticalpath 7. Coupling device 8 provides two first optical paths 6 and firstreference means 19 for the alignment. The space 16 is preferably filledwith a material having the same refractive index as the waveguide core11. Moreover the coupling device 8 comprises two optical components 15,which are lens arrays in this case. Finally the coupling device 8comprises third reference means 22 adapted to co-operate with the fourthreference means 28 of an optical connector 26 similar to that shown inFIG. 7D (but provided with a duplex arrangement of the relevant parts,such as the fourth reference means 28 and the means for providing twothird optical paths 27).

As was mentioned above, layer stack 1 may comprise, in the z-direction,multiple waveguide structures 3 in several, substantially parallel, x-yplanes. FIGS. 8A-D illustrate various embodiments according to theinvention, wherein a layer stack 1 comprises two waveguide structures 3in the z-direction, showing only the intersection with a singlewaveguide 2. It should be appreciated that the invention also can beapplied for more than two waveguide structures in the z-direction.

In FIG. 8A the layer stack 1 comprises two waveguides 2 or waveguidestructures 3 above each other. Each waveguide 2 provides a secondoptical path 7. Optical signals travelling along these second opticalpaths 7 are deflected by reflective layers 14, at least being applied onthe facets of the waveguides 2. Coupling device 8 comprises an area 18and provides two first optical paths 6 through optical components 15accommodated in the area 18. The optical components 15 are lenses inthis case. The space 16 is preferably filled with a material having thesame refractive index as the waveguide core 11. Alignment of thecoupling device 8 to the waveguides 2 or waveguide structures 3 as tooptically couple the first optical paths 6 and the corresponding secondoptical paths 7 in both the x- and y-direction of the x-y plane isperformed similar to the alignment process describes with reference toFIG. 3A-C.

In FIG. 8B deflection of optical signals between two first optical paths6 and corresponding second optical paths 7 is achieved by positioning amirror mount 17 integrated with the coupling device 8 in the opticalpaths 6 and 7. The rest of the connector assembly is, mutatis mutandis,similar to the embodiment shown in FIGS. 4A-D and the correspondingdescription. Alignment of the coupling device 8 to the waveguides 2 orwaveguide structures 3 as to optically couple the first optical paths 6and the corresponding second optical paths 7 in both the x- andy-direction of the x-y plane is performed similar to the alignmentprocess describes with reference to FIG. 3A-C. Z-axis control means,such as the space 23 under the mirror mount 17, the support structures24 and the adhesive substance 25, are not shown here. However, it willbe appreciated that these measured can be applied here as well.

In FIG. 8C a separate mirror mount 17 is applied as to deflect opticalsignal between the two second optical paths 7 and the correspondingfirst optical paths 6. The rest of the connector assembly is, mutatismutandis, similar to the embodiment shown in FIGS. 5A-C and thecorresponding description. Alignment of the coupling device 8 to thewaveguides 2 or waveguide structures 3 as to optically couple the firstoptical paths 6 and the corresponding second optical paths 7 in both thex- and y-direction of the x-y plane is performed similar to thealignment process describes with reference to FIG. 3A-C. Z-axis controlmeans, such as the space 23 under the mirror mount 17, the supportstructures 24 and the adhesive substance 25, are not shown here.However, it will be appreciated that these measured can be applied hereas well.

In FIG. 8D an alternative coupling device 8 is depicted, wherein thecoupling device 8 integrates an internal mirror 17. Coupling device 8further provides additional optical means 26, such as a lens or lensarray in the second optical paths 7 of the waveguide structures 3.

For the purpose of teaching the invention, preferred embodiments of theoptical connector assembly, the coupling device and the method foraligning have been described above. It will be apparent for the personskilled in the art that other alternative and equivalent embodiments ofthe invention can be conceived and reduced to practice without departingfrom the true spirit of the invention, the scope of the invention beingonly limited by the claims.

1. Optical connector assembly comprising a layer stack having at leastone waveguide structure in at least one x-y plane of said layer stack,and a coupling device providing at least one first optical path, saidwaveguide structure comprising at least one optical waveguide providingat least one second optical path deflecting from said first opticalpath, said coupling device comprising first reference means adapted toco-operate with second reference means in said layer stack, said secondreference means being adapted for aligning said coupling device to saidwaveguide or waveguide structure in both the x- and y-direction of saidx-y plane as to optically couple said first optical path and said secondoptical path, wherein said coupling device further includes an areacomprising an optical component for providing said first optical path.2. Optical connector assembly according to claim 1, wherein saidcoupling device comprises third reference means for aligning a matingoptical device, providing a third optical path, with said waveguide orwaveguide structure as to optically couple said second optical path andsaid third optical path.
 3. Optical connector assembly according toclaim 2, wherein said mating optical device comprises an opticalconnector having fourth reference means adapted to co-operate with saidthird reference means of said coupling device.
 4. Optical connectorassembly according to claim 2, wherein said third reference means andsaid fourth reference means are guide reference means.
 5. Opticalconnector assembly according to claim 1, wherein said optical componentis a lens or lens array.
 6. Optical connector assembly according toclaim 1, wherein said first optical path is deflected under a deflectionangle from said second optical path by a reflective layer applied on afacet of at least said waveguide or a mirror mount positioned in saidsecond optical path.
 7. Optical connector assembly according to claim 6,wherein said reflective layer(s) or said mirror mount are adapted todeflect optical signals between multiple first optical paths providedsaid coupling device and multiple corresponding second optical pathsprovided by multiple waveguides or waveguide structures.
 8. Opticalconnector assembly according to claim 6, wherein said mirror mountcomprises reference means to position said mirror mount in said secondoptical path.
 9. Optical connector assembly according to claim 6,wherein said mirror mount comprises further reference means to alignsaid mirror mount and said optical component, comprising correspondingreference means, as to optically couple said first optical path to saidsecond optical path.
 10. Optical connector assembly according to claim6, wherein at least one layer of said layer stack is adapted to positionsaid mirror mount in said second optical path.
 11. Optical connectorassembly according to claim 10, wherein said layer stack exhibits aspace under said mirror mount for fixing said mirror mount.
 12. Opticalconnector assembly according to claim 10, wherein said mirror mount issupported by a cladding layer of the waveguide or waveguide structure.13. Optical connector assembly according to claim 10, wherein saidmirror mount is supported by support structures.
 14. Optical connectorassembly according to claim 6, wherein said coupling device comprisessaid mirror mount.
 15. Optical connector assembly according to claim 6,wherein said mirror mount and said optical component are integrated insaid coupling device.
 16. Optical connector assembly according to claim1, wherein said first reference means and second reference means haverestricted dimensions in said x-y plane.
 17. Optical connector assemblyaccording to claim 1, wherein said first reference means and said secondreference means are guide reference means or index reference means. 18.Optical connector assembly according to claim 1, wherein said secondreference means are provided in one layer of said layer stack. 19.Optical connector assembly according to claim 1, wherein said secondreference means are located in the layer stack while said secondreference means remain available for aligning.
 20. Optical connectorassembly according to claim 19, wherein said second reference means arelocated in the layer stack corresponding to a layer of the waveguide orwaveguide structure.
 21. Optical connector assembly according to claim20, wherein said second reference means are located on top of the layerstack.
 22. Optical connector assembly according to claim 1, wherein saidlayer stack is a printed circuit board or backplane.
 23. Coupling devicefor use in a optical connector assembly according to claim
 1. 24.Coupling device according to claim 23, wherein said first referencemeans are guide reference means, said guide reference means defining aplane that is substantially parallel to said x-y plane.
 25. Method foraligning a coupling device, providing at least one first optical path,to at least one waveguide structure, comprising at least one opticalwaveguide, in at least one x-y plane of a layer stack, said at least onewaveguide providing at least one second optical path, deflecting fromsaid first optical path, said coupling device comprising first referencemeans, said method comprising the steps of applying second referencemeans in at least one layer of said layer stack in a predeterminedx-direction and y-direction relative to said waveguide structure;aligning said coupling device and said waveguide structure by matchingsaid first reference means in the x- and y-direction of said x-y planewith said second reference means, wherein said coupling device includesan area comprising an optical component providing at least a portion ofsaid first optical path which is aligned over a deflection point in saidlayered stack between said second optical path and said first opticalpath.
 26. Method according to claim 25, wherein said second referencemeans are applied in a layer of said layer stack corresponding to alayer of the waveguide or waveguide structure and/or on top of saidlayer stack.
 27. Method according to claim 25, wherein third referencemeans are applied on said coupling device for aligning a mating opticaldevice, providing a third optical path, with said waveguide or waveguidestructure as to optically couple said second optical path and said thirdoptical path.
 28. Method according to claim 27, wherein said firstreference means and said third reference means are applied inpredetermined positions relative to each other.
 29. Method according toclaim 27, wherein said first reference means and second reference meansare guide reference means or index reference means.
 30. Method accordingto claim 25, wherein a reflective layer is applied on a facet of saidwaveguide or a mirror mount is provided in said second optical path. 31.Method according to claim 30, wherein at least one layer of said layerstack is adapted to support said mirror mount or said coupling device insaid second optical path.
 32. Method according to claim 31, wherein saidmirror mount is supported by support structures provided in a space,said space at least substantially extending underneath said mirrormount.
 33. Method according to claim 30, wherein said mirror mount isfixed in said layer stack by providing an adhesive substance in at leasta part of said space underneath said mirror mount.
 34. Method accordingto claim 33, wherein said adhesive substance exerts a pulling force onsaid mirror mount to accurately position said mirror mount in saidsecond optical path.